Irrigation not only permits foodstuffs to be grown, but also enables the cultivation of attractive plant life that otherwise would not have sufficient water to thrive. Many households now utilize sprinkler systems to provide irrigation in a comparatively uniform and trouble-free manner.
Often, a control unit such as a timer is used to regularly initiate operation of the sprinkler system to automatically provide the desired distribution of irrigation water. The timer is electrically connected to a plurality of electrically operated valves, each of which is able to permit water to flow into a corresponding zone of the sprinkler system. Each zone may have a number of sprinklers, each of which is designed to distribute water in a predetermined pattern.
Sprinklers are available in a wide variety of different configurations, depending on the shape of the area to be irrigated. Some sprinklers spray water in a circular or part-circular pattern. For example, some sprinklers are designed to provide a quarter-circle pattern, while others spray water in half circle, three-quarters circle, or full-circle patterns. Additionally, some sprinklers are designed to irrigate a strip between a sidewalk and a street. Such sprinklers typically distribute water within a generally rectangular area. Strip sprinklers include multiple types, including center strip sprinklers, side strip sprinklers, and end strip sprinklers, depending on where the sprinkler is to be positioned within the strip.
A typical irrigation system includes a variety of sprinkler types, including several of the above. Consequently, the installer must have a relatively wide inventory of sprinklers available. The installer must carefully lay out the irrigation system prior to purchasing the components to obtain the correct quantity of each sprinkler type. A change in irrigation plans may necessitate additional trips to the store to purchase and/or exchange sprinklers. Some areas, such as those with corners between 90°, 180°, 270°, and 360°, are difficult or impossible to adequately or efficiently irrigate with the limited number of spray angles available. Furthermore, if the irrigation needs within a certain area change over time, one or more sprinklers may need to be replaced with different types.
In order to alleviate some of the foregoing problems, variable arc sprinklers have been developed. Many known variable arc sprinklers have two helical edges that define a slot. The angular width of the slot can be varied by rotating one helical edge with respect to the other to vary the magnitude of the angle within which water is sprayed from the sprinkler.
Unfortunately, known variable arc sprinklers have a number of inherent limitations. For example, many such sprinklers require axial (i.e., vertical) motion of the top end of the sprinkler to provide adjustment. Hence, even if the sprinkler is initially installed at the proper height, subsequent adjustment of the sprinkler may remove the top of the sprinkler from its initial position. Thus, the sprinkler may not have sufficient spray clearance, or may be damaged by lawn care equipment.
Furthermore, many known variable arc sprinklers are unable to provide an even distribution of water across the selected angle. Thus, the corresponding soil is unevenly irrigated. Many known variable arc sprinklers are unable to effectively provide full-circle coverage because the flow of water from the sprinkler head is discontinuous over the adjacent ends of the arc. Hence, even at a “full-circle” setting, there may be 5% or more along which water is not sprayed from the head, or is sprayed at such a low volume that corresponding region is not sufficiently irrigated.
Yet further, many known variable arc sprinklers are relatively complex, and are therefore far more expensive than their fixed-angle counterparts. Some known variable arc sprinklers have parts with relatively complex geometries that cannot be readily produced through the use of economical methods. Some adjustable sprinklers also have visible parts that are asymmetrical, and therefore may not look attractive to a user.
Still further, known variable arc sprinklers are generally not suitable for strip irrigation because they broadcast water over a pie-shaped or circular area that does not suit the dimensions of typical strips. Accordingly, the problems described above have not been fully remedied by existing sprinkler designs.